(1) Goals of Project: - To identify HIV-1 subunits which will generate widely cross neutralizing antibodies. - To identify a carrier which will increase the immunogenicity of the HIV-1 subunits, and will be able to recall anti-HIV B memory cells in patients with pre-existing immune deficiency. - To identify a carrier which would augment the TH1/TH2 ratio of infected individuals and will favor generation of cellular responses including cytotoxic cells (CTL). (2) Experimental approaches: - The gram negative Brucella abortus (Ba), and LPS derived from its cell wall (Ba-LPS), were tested as carriers for either inactivated HIV-1 virions, gp120 (SF2) glycoprotein, or peptide derived from the V3-loop of HIV-1 (MN) env. The different conjugates were used to immunize mice with different degrees of T cell deficiency. - In vitro studies with PBL from normal human as well as HIV-1 infected patients were assessed for their lymphokine production in response to Ba and Ba-LPS. Both PCR and biological assays were used. (3) Major findings: - Antibodies generated in mice against gp120-Ba and against V3-Ba were foun to be predominantly of the IgG 2a/2b subclasses. They neutralized several HIV-1 lab strains in a syncytia inhibition assay. - From a safety point of view, Ba or its LPS are much less toxic to animal than E. Coli derived LPS. - Ba and Ba-LPS were found to directly activate purified human CD4-positive TH1 cells, and to a lesser degree, CD8-positive cells, as judged by induction of the lymphokines IL2 and IFN-gamma. PBL from HIV-1 infected individuals were also responsive.